Pneumokok Pneumokok - 15 days ago 10
Java Question

JUnit, @ControllerAdvice and lack of checked exceptions in Kotlin

I wrote a validation advisor in Kotlin which throws

EntityValidationException
when validation fails:

@Aspect
@Named
class ValidationAdvisor
@Inject constructor(val validator: EntityValidator) {
@Around(EVERY_SAVE_AND_UPDATE_TO_DATABASE)
fun validate(point: ProceedingJoinPoint): Any {
val result: List<ConstraintViolation<Any>> = validator.validate(getEntity(point))
if (isEntityValid(result))
return point.proceed()

throw EntityValidationException(
violationInfos = result as List<ConstraintViolationInfo>
)
}

private fun getEntity(point: ProceedingJoinPoint): Any {
return point.args[0]
}

private fun isEntityValid(result: List<ConstraintViolation<Any>>): Boolean {
return result.isEmpty()
}

companion object {
const val EVERY_SAVE_AND_UPDATE_TO_DATABASE = "execution(* beans.repositories.BaseRepository.save(..))"
}
}


I have a JUnit test (I write some parts in Kotlin and some in Java, to learn Kotlin in existing private project) which checks if exception is thrown:

@Test(expected = EntityValidationException.class)
public void test_WhenNameIsNotPresent_ThenExceptionIsThrown() throws Exception {
repository.save(/* entity to save */);
}


But then I saw that test fails because it throws UndeclaredThrowableException instead of
EntityValidationException
. Next, I read that Kotlin does not have checked exception. I think not only me have this problem - I am pretty sure that way of handling exceptions with @ControllerAdvice in Spring and Java also may be problematic when we decide to switch to Kotlin in production projects - because it rely on class which is thrown, and throwing
UndeclaredThrowableException
take away from us this possibility. Is there a way to by-pass this behaviour, to make sure that is possible to switch to Kotlin and old Spring way of handling exceptions (and unit tests for
ValidationAdvisor
) will remain unchanged? Thank you in advance for any help.

P.S. Github repo for project is available here: Playgroud for Kotlin, Spring Data etc..

P.S.2 Stacktrace:

at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.run(SpringJUnit4ClassRunner.java:191)
at org.junit.runner.JUnitCore.run(JUnitCore.java:137)
at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:68)
at com.intellij.rt.execution.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:51)
at com.intellij.rt.execution.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:237)
at com.intellij.rt.execution.junit.JUnitStarter.main(JUnitStarter.java:70)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:497)
at com.intellij.rt.execution.application.AppMain.main(AppMain.java:147)
Caused by: java.lang.reflect.UndeclaredThrowableException
at com.sun.proxy.$Proxy65.save(Unknown Source)
at ActorValidationTest.test_WhenNameIsNotPresent_ThenExceptionIsThrown(ActorValidationTest.java:26)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:497)
at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50)
at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47)
at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
at org.junit.internal.runners.statements.ExpectException.evaluate(ExpectException.java:19)
... 26 more
Caused by: beans.validator.exceptions.EntityValidationException
at beans.aop.validation.ValidationAdvisor.validate(ValidationAdvisor.kt:23)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:497)
at org.springframework.aop.aspectj.AbstractAspectJAdvice.invokeAdviceMethodWithGivenArgs(AbstractAspectJAdvice.java:629)
at org.springframework.aop.aspectj.AbstractAspectJAdvice.invokeAdviceMethod(AbstractAspectJAdvice.java:618)
at org.springframework.aop.aspectj.AspectJAroundAdvice.invoke(AspectJAroundAdvice.java:70)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
at org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:92)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:213)
... 37 more


For me looks like
EntityValidationException
(which I want to be thrown) causes
UndeclaredThrowableException
.
EntityValidationException
Kotlin class code:

package beans.validator.exceptions

import beans.validator.constraintViolation.ConstraintViolationInfo

class EntityValidationException (val violationInfos: List<ConstraintViolationInfo>) : Exception() {
}


P.S.3 This also didn't work:

@Around(EVERY_SAVE_AND_UPDATE_TO_DATABASE)
@Throws(EntityValidationException::class)
fun validate(point: ProceedingJoinPoint): Any /* rest of code*/


P.S.4 Maybe the problem is that
@Aspect
is
@Around
Spring Data repository?

companion object {
const val EVERY_SAVE_AND_UPDATE_TO_DATABASE = "execution(* beans.repositories.BaseRepository.save(..))"
}
....
@NoRepositoryBean
public interface BaseRepository<ENTITY, IDENTIFIER extends Serializable>
extends JpaRepository<ENTITY, IDENTIFIER>, JpaSpecificationExecutor<ENTITY> {
}

Answer

You're trying to make the method save() or your repository throw a checked exception that it doesn't declare. So even if the aspect declares it, that can't work. You need to make your exception extend RuntimeException.

Comments